This invention relates to a fuel injection pumping apparatus for supplying fuel to internal combustion engines.
Examples of such apparatus are shown in Eurpean patent documents EP-A-0343759 (corresponding to U.S. Pat. No. 4,936,755) and EP-A-0423958(corresponding to U.S. Pat. No. 5,119,786). In such apparatus the maximum stroke of the piston is limited and is arranged to be at least just sufficient to absorb the total volume of fuel which can be displaced by the pumping plunger during its inward stroke. If in such apparatus the piston should seize within its cylinder or if the resilient biasing of the piston should fail then in the former case, the piston will be unable to move to absorb the spilled fuel and in the latter case if the piston is not already at the limit of its stroke, it will very quickly assume its limiting position. In both cases therefore irrespective of the operation of the spill valve the total volume of fuel displaced by the pumping plunger will be delivered to the associated engine. The increase in fuel flow to the engine will result in uncontrolled acceleration of the engine and the vehicle which is driven by the engine.